The complexes [Rh(CO)Cl(2-Ph2PC6H4COOMe)], 1, and trans-[Rh(CO)Cl(2-Ph2PC6H4COOMe)2], 2, have been synthesized by the reaction of the dimer [Rh(CO)2Cl]2 with 2 and 4 molar equivalents of 2-(diphenylphosphino)methyl benzoate. The complexes 1 and 2 show terminal ν(CO) bands at 1979 and 1949 cm−1 respectively indicating high electron density at the metal centre. The molecular structure of the complex 2 has been determined by single crystal X-ray diffraction. The rhodium atom is in a square planar coordination environment with the two phosphorus atoms trans to each other; the ester carbonyl oxygen atom of the two phosphine ligands points towards the rhodium centre above and below the vacant axial sites of the planar complex. The rhodium–oxygen distances (RhO(49) 3.18 Å; RhO(19) 3.08 Å) and the angle O(19)RhO(49) 179° indicate long range intramolecular secondary RhO interactions leading to a pseudo-hexacoordinated complex. The complexes 1 and 2 undergo oxidative addition (OA) reactions with CH3I to produce acyl complexes [Rh(COCH3)ClI(2-Ph2PC6H4COOMe)], 4, and trans-[Rh(COCH3)ClI(2-Ph2PC6H4COO-Me)(2-Ph2PC6H4COOMe)], 5, and the kinetics of the reactions reveal that the complex 1 undergoes faster OA reaction than that of the complex 2. The catalytic activity of the complexes 1 and 2 in the carbonylation of methanol were higher than that of the well known species [Rh(CO)2I2]− and the complex 1 shows higher activity than 2.